Earth’s north polar ice cap was smaller this past winter than at any time since measurements began to be obtained by satellite, breaking a record set only last year.

NASA and the National Snow and Ice Data Center announced March 28 that the maximum extent of ice during the season was reached on March 24 and that it covered 14.52 million square kilometers.

That beat last year’s mark of 14.54 million square kilometers and continued a stretch in which the 13 most ice-free winters in the Arctic have occurred in the past 13 years.

“It is likely that we’re going to keep seeing smaller wintertime maximums in the future because in addition to a warmer atmosphere, the ocean has also warmed up. That warmer ocean will not let the ice edge expand as far south as it used to,” Walt Meier, a sea ice scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, said. “Although the maximum reach of the sea ice can vary a lot each year depending on winter weather conditions, we’re seeing a significant downward trend, and that’s ultimately related to the warming atmosphere and oceans.”

During the most recent winter season the Arctic experienced record high temperatures in December, January, and February. Air temperatures were as much as 10 degrees Fahrenheit higher than average at the edge of the ice pack, Meier said.

Warm air from the south was brought by winds to the Arctic, which also would have contributed to a lessened sea ice cover.

Less winter sea ice causes the air temperature over the Arctic ocean to increase because the unfrozen ocean waters are warmer than the overlaying air mass. As the ocean water evaporates, more water vapor accumulates in the atmosphere and that, in turn, causes clouds to form. Increased cloudiness causes an increase in surface warmth.

Satellite measurements of Arctic winter ice extent began in 1979.

Since that time the Arctic has lost nearly 1,606 square kilometers of winter sea ice. That is an area twice the size of Texas.

Worldwide emissions of the greenhouse gas carbon dioxide increased by an unprecedented amount last year, according to the federal agency that monitors Earth’s climate.

The National Oceanic & Atmospheric Administration said Wednesday that the atmospheric concentration of CO2 reached 402.59 parts per million in February 2016. That was a jump of 3.05 parts per million, the largest in a 56 year-long history of record-keeping.

Confirmation of the data was provided by the Scripps Institution of Oceanography at the University of California at San Diego. However, researchers with that institution’s Scripps CO2 Group said that atmospheric concentration of carbon dioxide reached 404.16 parts per million last month.

The annual increase was greater than two parts per million for the fourth straight year.

“Carbon dioxide levels are increasing faster than they have in hundreds of thousands of years,” Pieter Tans, a scientist at NOAA’s Global Greenhouse Reference Network, said. “It’s explosive compared to natural processes.”

The Keeling curve shows the level of carbon dioxide, relative to other gases, in the atmosphere. Graphic courtesy Scripps Institution of Oceanography.

It has been about more than ten thousand years since Earth last experienced such a rapid increase in atmospheric carbon dioxide concentrations. Between 17,000 and 11,000 years ago the amount of CO2 in the atmosphere rose by 80 parts per million.

It is now rising at a pace 200 times faster than that, Tans said.

This graph shows the past four complete years and the current year of measurement, taken at Mauna Loa Observatory in Hawaii, of atmospheric carbon dioxide levels. The dashed red line with diamond symbols represents the monthly mean values, centered on the middle of each month. The black line with the square symbols represents the same, after correction for the average seasonal cycle. Graphic courtesy NOAA.

NOAA said in a statement that the current El Niño event is contributing to the CO2 increase, but that fossil fuel combustion remains the overwhelming driver of greenhouse gas accumulation in the atmosphere.

Winter in the northern hemisphere is not quite over (the spring equinox is March 20), but it is already clear that, at least in the continental United States, there hasn’t been a winter like it since at least 1894.

The National Oceanic & Atmospheric Administration said Tuesday that the average temperature this season throughout the contiguous 48 states was 4.6 degrees Fahrenheit above average. The mean temperature on the mainland U.S. was 36.8 degrees Fahrenheit between December and February.

The previous record high winter temperature was set during 1999-2000.

Graphic courtesy NOAA

El Niño may have contributed, at least to some extent, to the unusually warm winter temperatures. The current ENSO is among strongest since at least 1950; a NOAA blog described it last summer as the “Bruce Lee of Niños.”

During an El Niño event the temperature of ocean water in the eastern Pacific rises beyond the normal range. The warmer ocean water off the west coast of South America drives changes in the jet stream, which in turn tends to cause winter temperatures in North America to be higher than they ordinarily would and increased precipitation in the southern portion of the continent. This explanation from a NOAA blog may be helpful:

Warmer tropical Pacific waters release more heat to the atmosphere, causing more rising air and storminess in the central and eastern tropics. The rising air moves north (and south) away from the tropics, traveling to the mid-latitudes, where it shifts the North Pacific jet stream farther southward and eastward. Movement and extension of the jet stream can bring more storms to the United States, and change the seasonal temperature and precipitation patterns.

This graphic shows typical ENSO warm episode impacts. Note that those impacts are not uniform throughout the world. Some areas can be warmer or cooler than others during this type of event. Graphic courtesy NOAA.

In fact, winter has been wet in North America this year. NOAA reported that, during the December-February period, the continental U.S. received the twelfth-most amount of precipitation for that time interval in recorded history.

The term El Niño is a Spanish phrase that means “little boy.” According to a University of Washington website:

The name El Niño (referring to the Christ child) was originally given by Peruvian fisherman to a warm current that appeared each year around Christmas. What we now call El Niño seemed to them like a stronger event of the same type, and the usage of the term changed to refer only to the irregular strong events. It wasn’t until the 1960s that it was widely realized that this was not just a local Peruvian occurrence, but was associated with changes over the entire tropical Pacific and beyond.

The opposite of El Niño is La Niña, which is marked by water temperatures in the eastern Pacific Ocean and near the equator that are below average.

Measurement of the extent to which ongoing anthropogenic climate change has driven the high temperatures experienced in the U.S. this winter is difficult. However, it is clear that ocean water temperatures are rising as greenhouse gases continue to be emitted to the atmosphere. This happens because, as the temperature of the air in Earth’s lower atmosphere rises, the oceans absorb some of the heat.

The oceans are now warmer than they have been in at least 50 years.

The surface of the world’s oceans has become warmer overall since 1880. In this graph, the shaded band shows the likely temperature range, which depends on the number of measurements and the methods used at different times. Source: U.S. Environmental Protection Agency, Climate Change Indicators (2014). Graphic courtesy U.S. Environmental Protection Agency.

The rising temperature of the oceans does likely cause warmer winter temperatures in at least some areas of the globe. When liquid water is heated, the molecules of the compound evaporate into a gas called water vapor. The process of evaporation adds heat to the surrounding atmosphere.

Earth experienced its first total solar eclipse since March 20, 2015 on Tuesday, with Indonesia being the locale on the planet where the spectacle could be seen.

The eclipse began at 8:38 pm EST and lasted for four minutes. It was visible to people in about half of Indonesia’s provinces. A report in the New York Times said that the town of Ternate, located in the Maluku Islands, was the “prime viewing location.”

A partial solar eclipse could be observed elsewhere in the south Pacific region, including in Hawaii.

Solar eclipses occur when the Moon passes between Earth and its star, temporarily blocking some or most of the sun’s light from reaching Earth. The event happens only about once per year because the plane of Moon’s orbit does not exactly match Earth’s orbit around the sun.

The Moon seems to block the sun because, while the sun is about 400 times larger than the Moon, it is also about 400 times farther away.

This image shows Tuesday’s eclipse in progress from South Tangerang, Indonesia:

Ecuador’s Tungurahua volcano began to erupt last Friday, Feb. 26, sending ash and smoke into the atmosphere in a series of explosions. This BBC video shows some of the action:

Tungurahua is a stratovolcano – a stratified, conical volcano that is both aesthetically pleasing and very dangerous. Stratovolcanoes, also called composite volcanoes, tend to be concentrated in areas where a plate of Earth’s crust subducts below another.

This schematic diagram shows the internal structure of a typical stratovolcano. Image courtesy U.S. Geological Survey.

Tungurahua is part of a chain of volcanoes that populates the Andes mountains. The Andean Volcanic Belt is a consequence of the subduction of the Nazca and Antarctic plates below the South American plate.

The mountain, whose name may mean “throat of fire,” is one of 28 active volcanoes in Ecuador.

All of that South American country’s volcanoes are part of the Ring of Fire. That belt of volcanoes largely encircles the Pacific Ocean and includes 452 volcanoes, about 75 percent of the world’s total.

The mountain has a peak more than 16,000 feet above sea level.

Tungurahua has now erupted three times since 2010. Those eruptions are part of a cycle that began in 1999. Prior episodes of eruptive activity occurred in 1773, 1886, and 1916-1918.

More than 20,000 people live within ten kilometers of Tungurahua. Ecuador’s capital city, Quito, is about 140 kilometers north of the volcano. Tungurahua is located within Sangay National Park.

Tungurahua is shown erupting at night during July 2015. Photo courtesy National Polytechnic School, Geophysics Department.

Mount Sinabung is also a stratovolcano and is located on the island of North Sumatra. Before eruptions in 2010, 2013, and 2014, the volcano was last active in the 1600s. There are four craters on the mountain. Mount Sinabung’s peak sits at an elevation of about 8,069 feet.

More than 13,000 people live within 10 kilometers of Sinabung, according to the Smithsonian Institution’s Global Volcanism Program website.